Contact: David Sims
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Science WriterInstitute for the Study of Earth, Oceans, and Space

February 21, 2007

Note to Editors and Reporters: Journalists should seek to credit the relevant Nature publication as the source
of stories covered. Mark Fahenstock can be reached at mark.fahnestock@unh.edu.

DURHAM, N.H. --
One of the planet's most remote and little-understood features
may play a crucial role in transporting ice from the remote interior of Antarctica
towards the surrounding ocean and therefore impact sea level rise and regional
and global climate change, according to a new research published in the February
22 issue of the journal Nature.

A team of scientists led by geophysicists Robin Bell and Michael Studinger
from the Lamont-Doherty Earth Observatory at Columbia University, and including
glaciologist Mark Fahnestock of the University of New Hampshire and colleagues
from NASA and the University of Washington, discovered four large, subglaical
lakes and, for the first time, linked these water bodies locked beneath miles
of ice to fast flowing ice streams in Antarctica.

The scientists found that four separate lakes appear to contribute to the
formation of an ice stream. Ice streams are large, fast-flowing features within
ice sheets that transport land-based ice and meltwater to the ocean. One such
stream, the Recovery Ice Stream, drains eight percent of the U.S.-sized East
Antarctic Ice Sheet. The Recovery basin, unexplored since 1966, funnels an
estimated 35 billion tons of ice into the Weddell Sea annually.

“It has been a puzzle to us why, in a few cases, ice streams reach well
into the interior of the large ice sheets,” said Fahnestock of the UNH
Institute for the Study of Earth, Oceans, and Space (EOS). Fahnestock added, “These
lakes at the head of the Recovery system provide a compelling explanation.”

Until about a year ago, not many people cared much about subglacial lakes,
according to Studinger of Columbia University. "That's changing, but we're
still only just beginning to understand how these lakes, sealed beneath more
than two miles of ice, have the potential to impact the rest of the world," he
said.

The scientists examined satellite radar images and high-resolution laser profiles
of the region for ice stream patterns and surface features indicating the presence
of subglacial lakes beneath the ice. Not only did they find four new lakes,
but they discovered that the lakes coincide with the origin of tributaries
of the Recovery Glacier. Upstream of the lakes, the ice sheet moves at just
2 to 3 meters per year; downstream the flow increases to nearly 50 meters per
year. The scientists conclude that the lakes provide a reservoir of water that
lubricates the bed of the stream to facilitate ice flow and prevent the base
of the sheet from freezing to the bedrock.

Moreover, their work suggests that subglacial lakes could play a role in and
sea level rise as well as regional and global climate change. Meltwater at
the base of ice streams increases the flow of ice to the oceans, which could,
in turn, contribute to higher sea levels worldwide. In addition, floods have
been known to originate from the interior of the ice sheet in the past, possibly
from subglacial lakes. These sudden pulses of fresh water could potentially
interfere with nearby ocean currents that redistribute heat and carbon dioxide
around the globe, disrupting the Earth's finely tuned climate system.

"It's almost as if the lakes are capturing the geothermal energy from
the entire basin and releasing it to the ice stream." said Bell. "They
power the engines that drive ice sheet collapse. The more we learn about them,
the more we realize how important they are."

Photo caption: Combined RADARSAT and ICESat images showing the Recovery Glacier
Ice Stream (arrows) and location of four new subglacial lakes (A, B, C and
D) that lie at the head of the stream. Credit: Chris Shuman and Vijay Suchdeo,
NASA.